Going With Your Gut: The (In)accuracy of Forecast Revisions in a Football Score Prediction Game

Abstract

We study individuals who each chose to predict the outcome of fixed events in an online competition, namely all football matches during the 2017/18 season of the English Premier League. We ask whether any forecast revisions the individuals chose to make (or not), before the matches began, improved their likelihood of predicting correct scorelines and results. Against what theory might expect, we show how revisions tended towards significantly worse forecasting performance, suggesting that individuals should have stuck with their initial judgements, or their `gut instincts'. This result is robust to both differences in the average forecasting ability of individuals and the predictability of matches. We find evidence that this is because revisions to the forecast number of goals scored in football matches are generally excessive, especially when these forecasts were increased rather than decreased.